The home and project file systems are backed up, with a target backup window that runs once per 24 hours to disk-based storage.
The criteria for backing up a file is a change in UNIX ctime, mtime or file size. Once a version of a file has been successfully backed up, its contents will be retained for 30 days upon being removed or changed on the file system.
The purpose of the backups is to protect against catastrophic hardware failures, not accidental deletions or overwrites. See Protecting from accidental loss.